Influenza virus nucleoprotein and matrix protein M1 (NP/M1)

Influenza virus nucleoprotein (NP) and matrix protein M1 are internal structural proteins that are highly conserved across different strains of the influenza virus. NP is an essential RNA-binding protein that encapsidates the viral genome into ribonucleoprotein (vRNP) complexes, which are necessary for viral replication and transcription (UniProt P03466). M1 forms a structural layer beneath the viral lipid envelope, facilitating the assembly of new virions and the nuclear export of vRNPs (UniProt P03485). In split-virion and subunit vaccine preparations, these proteins are present as minor components following the detergent-mediated disruption of the virus (CDC, 2023). Because they are much more conserved than the surface antigens hemagglutinin and neuraminidase, NP and M1 are primary targets for inducing heterosubtypic or "universal" immunity, primarily through the activation of cross-reactive cytotoxic T lymphocytes (PubMed: 23658377). Therapeutic development focusing on these targets includes experimental viral-vectored vaccines like MVA-NP+M1 and small-molecule inhibitors like Nucleozin, which aims to disrupt NP polymerization and viral genome packaging (Nature Biotechnology, 2010).

Other names

Influenza internal proteinsNucleoprotein (NP)Matrix protein 1 (M1)Nucleocapsid proteinMinor components of split-virion vaccinesInfluenza A virus structural proteins

Induction of cross-reactive CD8+ and CD4+ T-cell responses; inhibition of viral ribonucleoprotein (vRNP) assembly and nuclear export.